Bark and wood fiber growing medium

ABSTRACT

A method for making a growing medium includes a step of combining tree bark and/or wood components together to form an initial composition; heating the initial composition to a temperature greater than about 149° C. under steam in a pressurized vessel; processing the initial composition through a refiner with a plurality of opposing disks to obtain the fibrous growing medium, the refiner separating fibers from each other; wherein the growing medium has total porosity of 88 volume % or more.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/589,694, filed Oct. 1, 2019, (pending), which is a continuation ofU.S. application Ser. No. 16,366,319, filed Mar. 27, 2019, now U.S. Pat.No. 10,519,073, issued Dec. 31, 2019, which is a continuation of U.S.Ser. No. 15/400,363, filed Jan. 6, 2017, now U.S. Pat. No. 10,266,457,issued on Apr. 23, 2019, which is a continuation-in-part of U.S. Ser.No. 15/322,906, filed Dec. 29, 2016, now U.S. Pat. No. 10,519,373,issued on Dec. 31, 2019, which is a 371 of InternationalPCT/US2015/038312, filed Jun. 29, 2015 (now expired) which claims thebenefit to U.S. provisional application Ser. No. 62/018,640, filed Jun.29, 2014 (expired), the disclosures which are incorporated in theirentirety by reference herein.

TECHNICAL FIELD

The present invention is related to a substrate that can be used as areplacement for peat in a growing medium.

BACKGROUND

Peat is a widely used organic material for agricultural andhorticultural applications. Peat is used to improve soil structure,retain moisture, and increase acidity. Peat is also frequently addedinto agricultural mixes to increase water-holding capacity and/or todecrease weight. Since peat is typically harvested from natural sourcessuch as mires and peat lands, mining of peat presents a threat tofragile peat bog ecosystems by disrupting wildlife habitats andendangering endemic species. Peat lands also contribute to healthywatersheds and aid in providing safe drinking water for humanpopulations. Besides their water filtration capabilities, peat bogs areeffective in flood prevention and serve as a very efficient carbon sink.Thus, there is a desire to preserve peat lands and to decreasecommercial use of peat.

Various substitutes for peat have been suggested, for example, coir orcoconut fiber derived from the husk of the coconut fruit, wood-basedsubstrates, or rice hulls. Yet, all of these substitutes suffer from avariety of drawbacks. For example, neither substitute provides asatisfactory volume of air space. The substitutes also have a relativelyhigh dry and wet bulk density, thus contributing to a relatively highweight of products which include the substitute. Additionally, some ofthe substitutes may be, just like peat, available only on a limitedbasis, and their harvesting may have environmental implications.

Accordingly, there is a need for peat replacements that do notnegatively impact the environment and which provide desirable propertiesto a growing medium.

SUMMARY OF THE INVENTION

The present invention solves one or more problems of the prior art byproviding a mulch composition or growing medium including fibrous woodcomponents. The mulch composition or growing medium is made by a methodwherein fibrous wood components are combined together to form an initialcomposition which is heated to a temperature greater than about 300° F.(about 149° C.) under steam in a pressurized vessel and fiberized in arefiner to form the fibrous growing medium. The resultant fibrous mulchcomposition or growing medium has total porosity of 88 volume % or more.The mulch composition or growing medium has a dry bulk density of about80 kg/m³ or lower and wet bulk density of about 120 kg/m³ or lower. Themulch composition or growing medium is ideal as a standalone mulchcomposition or growing medium as well as an additive to peat-basedsubstrates, and to amend other existing substrates. The mulchcomposition or growing medium can also be used to displace at least aportion of peat, composted pine bark, perlite, vermiculite, sand, rockwool, compost, animal manure, rice hulls, hardwood bark, softwood bark,coir, the like, or a combination thereof in various growing mixes orsubstrates.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a schematic flowchart illustrating the formation of thegrowing medium;

FIGS. 2A and 2B show stereoscopic images of coir particles of #16 sieveand #50 sieve, respectively;

FIGS. 3A and 3B show stereoscopic images of peat particles of #16 sieveand #50 sieve, respectively;

FIGS. 4A and 4B show stereoscopic images of bark particles of #16 sieveand #50 sieve, respectively;

FIGS. 5A and 5B show stereoscopic images of Pine Tree Substrate (PTS)particles of #16 sieve and #50 sieve, respectively;

FIGS. 6A and 6B show stereoscopic images of perlite particles of #16sieve and #50 sieve, respectively;

FIGS. 7A and 7B show stereoscopic images of Whole Tree Substrate (WTS)particles of #16 sieve and #50 sieve, respectively;

FIGS. 8A and 8B show stereoscopic images of growing medium fibers of #16sieve and #50 sieve, respectively; and

FIGS. 9 and 10 show retention curve comparisons of various substrates.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figure is not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

The term “dominant wavelength” refers to a way of describingpolychromatic light mixtures in terms of monochromatic light that evokesan identical perception of hue. It is determined on the InternationalCommission on Illumination (CIE)'s color coordinate space by a straightline between the color coordinates for the color of interest and thecoordinates for the illuminate. The intersection at the perimeter of thecoordinate space nearest the color of interest is the dominantwavelength.

The term “growing medium” (GM) refers to a substrate, specifically asoil-free substrate or a substrate with soil, or a combination ofmaterials used to provide physical support, water retention, aeration,and/or nutrient supply for plant growth so that a plant can establishits root system within the growing medium and allow for root growth, asthe roots grow in spaces between individual particles of the growingmedium.

The term “mulch” or “mulch composition” as used herein means a layer offibrous material that is applied to a soil to reduce erosion, to improvewater retention, and/or to hold a seed in place on the soil surface longenough for the seed to germinate and for the root to develop within thesoil below the mulch. Hydraulic mulches are mulches applied by sprayingwith water through a hydraulic seeder or similar device. The terms“growing medium” and “mulch composition” are used interchangeably.

The mulch composition or growing medium may include one or more woodcomponents. The term “wood components” or “fibrous wood components”refers to wood chips, wood fiber, bark, needles, or their combination.The wood components may be derived from coniferous and deciduous treesand may be prepared by any convenient manner, for example as disclosedfor wood fibers in U.S. Pat. No. 2,757,150. Any type of wood componentsmay be used, but wood components of the softwood varieties such asyellow poplar, cedar such as Western red cedar, fir such as Douglas fir,California redwood, and particularly pine such as Ponderosa, Sugar,White, and Yellow varieties of pine are preferred. For example, fibrouswood components may refer to fibrous pine tree wood components includingjust fibrous pine tree wood or fibrous pine tree wood as well as fibroustree bark, needles, chips, or a combination thereof.

The mulch composition or growing medium, and in particular, a fibrousmulch composition or growing medium, may include about 5 to about 95weight % of tree bark mixed with about 95 to about 5 weight % of woodcomponents, based on the total weight of the mulch composition orgrowing medium. The mulch composition or growing medium may include 100weight % fibrous pine wood components. The mulch composition or growingmedium may include about 10 weight % of tree bark and about 90 weight %of wood components, based on the total weight of the mulch compositionor growing medium. The mulch composition or growing medium may includeabout 20 to about 70 weight % of tree bark and about 30 to about 80weight % of wood components, based on the total weight of the mulchcomposition or growing medium. Alternatively, the mulch composition orgrowing medium may include about 50 to about 60 weight % of tree barkand about 40 to about 50 weight % of wood components, based on the totalweight of the mulch composition or growing medium. The mulch compositionor growing medium may include about 90 weight % of tree bark and about10 weight % of wood components, based on the total weight of the mulchcomposition or growing medium. The mulch composition or growing mediummay further include about 0 to about 10 weight % or more of additionalcomponents, based on the total weight of the mulch composition orgrowing medium, as set forth below. Throughout the entire disclosure,unless otherwise specified, all weight percentages of components arebased on the total weight percent of the components in the growingmedium which is 100% by weight. In addition, unless otherwise specified,all volume percentages of components are based on the total volumepercent of the components in the growing medium which is 100% by volume.

The tree bark may contain one or more pigments or pigment precursorsthat give color to its layers. Some bark (for example eucalyptus barkand sycamore bark) may be light-colored initially, but darken after itspigments are oxidized. Pigments included in the bark may include, butare not limited, to tannins such as tannic acid (e.g., quercitannic acidand gallotanic acid). Non-limiting examples of useful tree barkscontaining one or more pigments are named above. In addition, duringheat treatment, additional pigments may develop in the bark, in thewood, or both, which contribute to the color of the mulch product or thegrowing medium. This is what is meant by “pigment precursors.”

The amount, age, moisture, and/or other properties of the bark used mayinfluence hue and/or intensity of the imparted color. For example, lowquantities of bark may result in light brown color of the mulchcomposition or growing medium while high quantities of bark may resultin dark brown color. At least about 1 weight %, about 3 weight %,preferably about 5 weight % of bark may be needed to obtain mulch orgrowing medium dyed by the bark pigments. To color-change the mulch orgrowing medium, about 1 to about 99 weight % of bark may be included inthe initial composition, based on the total weight of the initialcomposition. Additional bark may be added during the process ofproducing mulch or growing medium so that the final color of the fiberproduct may be adjusted to the desired hue. Concerning the age of bark,the bark from the most recently debarked trees generally provides forthe most intense color change of the wood components. Moisture of thebark may be about 30 to 60%, measured by ASTM D4442-07, to provideadequate color change of the wood components.

The mulch composition or growing medium may have a color with a dominantwavelength from about 510 nm to about 780 nm, about 590 nm to about 770nm, about 620 nm to about 760 nm, or about 675 nm to about 750 nmrelative to a white illuminate. The mulch composition or growing mediummay have a red to brown to black color. The mulch composition or growingmedium may have a yellow, orange, gray, or green color. The mulchcomposition or growing medium may have hsl color coordinates such thatthe “h value” (hue) is from about 25 to about 45, the “s value”(saturation) is from about 20 to about 100, and the “1 value”(lightness) is less than about 50. The 1 value may be from about 0 toabout 25.

The mulch composition or growing medium may further include anon-permanent dye that is eventually removed or that eventually fadesafter the composition is applied. Preferably, the non-permanent dye isnon-toxic so that no toxic chemicals are leached from the mulchcomposition or growing medium into the environment. The non-permanentdye may comprise natural and/or synthetic compounds. The non-permanentdye may comprise compounds derived from plants, fungi, lichens,invertebrates, insects, minerals, the like, or a combination thereof.Any part of the plant may be utilized to provide the dye such as roots,petals, leaves, stems, shoots, stalks, hulls, husks, ripe and/or unripefruit, or seed. Exemplary sources of plant dyestuffs include treevarieties named above; vegetables such as carrots, beetroot, redcabbage, artichoke, spinach, celery; fruit such as blueberries,pomegranate, strawberries, avocado, cherries, raspberries, mulberries,elderberries, blackberries, grapes, peach; turmeric, fennel, basil,paprika, saffron, tea plants, coffee plants, barberry, bloodroot, lilac,coneflower, dandelion, goldenrod, hollyhock, ivy, St John's Wort, yellowdock, rose, lavender, cornflower, hyacinth, Queen Anne's Lace, hibiscus,daylily, safflower, camellia, snapdragon, nettle, milkweed, peony,Black-eyed Susan, hydrangea, chamomile, alfalfa, crocus, marigold, orthe like. Exemplary mineral-based dyestuffs include iron oxide andcarbon black. Exemplary useful non-permanent dye includes ELCOMENT BLACK7822 commercially available from Greenville Colorants. Another exemplarytype of non-permanent dye may include green pigments.

The non-permanent dye may be combined with the bark alone and/or withthe components alone before the initial composition is formed beforestep a), with the initial composition in step a), with the mulchcomposition or growing medium in step b), in step c), in step d), instep e), after step e), or in more than one step. At least about 0.1 toabout 2 weight % of non-permanent dye may be added to the initialcomposition to cause color change of the wood fiber, based on the totalweight of the initial composition. About 0.1 to 15 weight % or more,about 2 to 10 weight %, about 3 to 7 weight % of the non-permanent dyemay be added to the initial composition, based on the total weight ofthe initial composition. At least about 2-40 pounds (0.9-18 kg) ofnon-permanent dye may be added per ton of the final mulch or growingmedium to achieve color change.

Typically, the removable non-permanent dye imparts a darker color on themulch composition or growing medium than when the non-permanent dye isabsent therein. The non-permanent dye may be washed away after severaldays (about 1 to about 30 days or after more extensive time period)after being applied in the field. The non-permanent dye may fade away orbegin to fade away (e.g., from exposure to sunlight or otherenvironmental conditions) after several days such as about 1 to about 30days or after more extensive time period after being applied in thefield.

The mulch composition or growing medium with the non-permanent dye mayhave a color with a dominant wavelength from about 400 nm to about 780nm, about 510 nm to about 770 nm, about 590 nm to about 760 nm, or about620 nm to about 750 nm relative to a white illuminate. The color of themulch composition or growing medium including the non-permanent dye mayvary. The fiber-containing product with the non-permanent dye may have ared to brown to black color. But other colors such as green, blue,yellow, orange, purple, or gray hues are contemplated as well. The typeand amount of dye determine intensity of the color. Typically, theremovable non-permanent dye imparts a darker color on thefiber-containing product than when the non-permanent dye is absenttherefrom. Alternatively, the fiber-containing product with thenon-permanent dye may have a lighter color than when the non-permanentdye is absent therefrom. The fiber-containing product may have a lower“h value” than the fiber-containing product without the non-permanentdye. The mulch composition or growing medium may have hsl colorcoordinates such that the “h value” (hue) is from about 10 to about 40,the “s value” (saturation) is from about 20 to about 100, and the “1value” (lightness) is less than about 50. The 1 value may be from about0 to about 25.

The mulch or growing medium may be dyed by bark pigments and/or by oneor more natural non-permanent dyes in order to comply with organicstandards and secure a certificate from the Organic Materials ReviewInstitute (OMRI).

The dyed fiber produced by the method described above and the resultingmulch or growing medium composition may have a light-fastness, in orderof increasing preference, of at least up to 1 day, 5 days, 10 days, 20days, 1 month, 2 months, or 3 months or more, with minimal fading,measured according to ASTM D4303-99. The term “minimal fading” refers toany visually discernable extent of fading. The light-fastness of thedyed mulch or growing medium may be about 1 to 120 days, about 5 to 90days, about 10 to 30 days.

As set forth above, the mulch composition or growing medium may includetree bark. The term “bark” refers to a plurality of stem tissuesincluding one or more of cork (phellum), cork cambium (phellogen),phelloderm, cortex, phloem, vascular cambium, and xylem. Examples ofuseful tree barks include, but are not limited to, bark from pine, oak,walnut, mahogany (Swietenia macrophylla, Swietenia mahagoni, Swieteniahumilis), hemlock, Douglas fir, alder, elm, birch, Sitka spruce,sycamore, and the like, and combinations thereof. Pine tree bark isfound to be particularly useful in the growing medium.

The input bark and/or wood components may be preprocessed in a varietyof ways such as cut so that the dimensions of the input wood componentsand/or bark pieces are about 0.25 inches (0.64 cm) to about 6 incheslong and wide, about 1 inch (2.54 cm) to about 4 inches (10.2 cm) longand wide, about 2 inches (5 cm) to about 3 inches (7.6 cm) long andwide. Preferably, the size of the wood components and/or bark pieces isabout 2×2 inches (5×5 cm).

The initial density of the wood components and/or bark before the woodcomponents and/or bark are formed into a mulch composition or growingmedium by the process described below may be about 15 lbs/ft³ (240.28kg/m³) to about 35 lbs/ft³ (560.65 kg/m³).

The fibrous mulch composition or growing medium may be combined withadditional components. Examples of such additional components include,but are not limited to, fertilizer(s), macronutrient(s),micronutrient(s), mineral(s), binder(s), natural gum(s), interlockingmanmade fiber(s), and the like, and combinations thereof. In general,these additional components in total are present in an amount of lessthan about 10 weight % of the total weight of the mulch composition orgrowing medium. More preferably, the additional components in total arepresent in an amount from about 1 to about 15 weight % of the totalweight of the mulch composition or growing medium. Additionally, soilmay be present in an amount of about 20 weight % or less, about 15weight % or less, or about 5 weight % or less of the total weight of themulch composition or growing medium. The soil may be present in anamount of about 0.1 to about 20 weight % of the total weight of themulch composition or growing medium. Soil may also be absent from themulch composition or growing medium.

Fertilizers such as nitrogen fertilizers, phosphate fertilizers,potassium fertilizers, compound fertilizers, and the like may be used ina form of granules, powder, prills, or the like. For example,melamine/formaldehyde, urea/formaldehyde, urea/melamine/formaldehyde andlike condensates may serve as a slow-release nitrogenous fertilizer.Fertilizers having lesser nutritional value, but providing otheradvantages such as improving aeration, water absorption, or beingenvironmental-friendly may be used. The source of such fertilizers maybe, for example, animal waste or plant waste.

Nutrients are well-known and may include, for example, macronutrient,micronutrients, and minerals. Examples of macronutrients includecalcium, chloride, magnesium, phosphorus, potassium, and sodium.Examples of micronutrients are also well-known and include, for example,boron, cobalt, chromium, copper, fluoride, iodine, iron, magnesium,manganese, molybdenum, selenium, zinc, vitamins, organic acids, andphytochemicals. Other macro- and micronutrients are well known in theart.

The binders may be natural or synthetic. For example, the syntheticbinders may include a variety of polymers such as addition polymersproduced by emulsion polymerization and used in the form of aqueousdispersions or as spray dried powders. Examples includestyrene-butadiene polymers, styrene-acrylate polymers, polyvinylacetatepolymers, polyvinylacetate-ethylene (EVA) polymers, polyvinylalcoholpolymers, polyacrylate polymers, polyacrylic acid polymers,polyacrylamide polymers and their anionic- and cationic-modifiedcopolymer analogs, i.e., polyacrylamide-acrylic acid copolymers, and thelike. Powdered polyethylene and polypropylene may also be used. Whenused, synthetic binders are preferably used in aqueous form, for exampleas solutions, emulsions, or dispersions. While binders are notordinarily used in growing media, they may be useful in hydraulicallyapplied growing media.

Thermoset binders may also be used, including a wide variety of resoleand novolac-type resins which are phenol/formaldehyde condensates,melamine/formaldehyde condensates, urea/formaldehyde condensates, andthe like. Most of these are supplied in the form of aqueous solutions,emulsions, or dispersions, and are generally commercially available.

The natural binder may include a variety of starches such as cornstarch, modified celluloses such as hydroxyalkyl celluloses andcarboxyalkyl cellulose, or naturally occurring gums such as guar gum,gum tragacanth, and the like. Natural and synthetic waxes may also beused.

With reference to FIG. 1, a schematic flowchart illustrating theformation of the mulch composition or growing medium is provided. As canbe seen in FIG. 1, in step a), an initial composition 14 is formed bycombining tree bark 10 and/or wood components 12 together to form theinitial composition 14. The wood components 12 may include wood chips,wood fiber, needles, or a combination thereof; yet, preferably, the woodcomponents are wood chips. Typically, about 1 to about 99, 90, 85, 80,75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 5 weight % oftree bark, such as pine, is combined with about 99, 95, 90, 85, 80, 75,70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 5, 1 weight % ofwood components, based on the total weight of the mulch composition orgrowing medium, in step a). Alternatively, about 5 to about 95 weight %of tree bark is combined with about 95 to about 5 weight % of woodcomponents, based on the total weight of the mulch composition orgrowing medium, in step a). Alternatively, still, about 20 to about 70weight % of tree bark is combined with about 30 to about 80 weight % ofwood components, based on the total weight of the mulch composition orgrowing medium, in step a). In another embodiment, about 50 to about 60weight % of tree bark is combined with about 40 to about 50 weight % ofwood components, based on the total weight of the mulch composition orgrowing medium, in step a). In yet another embodiment, the initialcomposition 14 may be substantially bark free and contain about 100weight % of wood components, based on the total weight of the mulchcomposition or growing medium.

Based on the total volume of the mulch composition or growing medium,about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14 16, 18, 20, 25,30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 volume % of treebark, such as pine, may be combined with the remainder of woodcomponents in step a).

In step b), the initial composition 14 is heated to an elevatedtemperature to kill microbes in a pressurized vessel 16. Typically, theheating step may be conducted at a temperature in the range of about250° F. (121° C.) or lower to about 500° F. (260° C.) or higher, about300° F. (149° C.) to about 400° F. (204° C.), about 320° F. (160° C.) to380° F. (about 193° C.). The heating step may be conducted for a timesufficient to kill microbes. The heating step may be conducted for about1 to about 5 minutes or longer under a steam pressure of about 35lbs/in² (2.4 kg/cm²) to about 120 lbs/in² (8.4 kg/cm²) or about 50lbs/in² (3.5 kg/cm²) to about 100 lbs/in² (7.0 kg/cm²). For example, theheating step may be conducted at a temperature of about 300° F. (149°C.) for about 3 minutes at about 80 lbs/in² (5.6 kg/cm²). For example,the heating step may be conducted at a temperature of about 300° F.(149° C.) for about 3 minutes. The heating step results in a preferablysubstantially sterile mulch composition or growing medium such that themulch composition or growing medium is free from bacteria or otherliving organisms. The steam flow rate during the heating step may befrom about 4000 lbs/hour (1814 kg/hour) to about 15,000 lb/hour (6803kg/hour).

An example of a pressurized vessel and related process for step b) isdisclosed in U.S. Pat. No. 2,757,150, which has been incorporated byreference, in which wood chips are fed to a pressurized steam vesselwhich softens the chips. Any type of wood chip may be used in thisprocess, but wood chips of the softwood varieties such as yellow poplar,and particularly pine, are preferred.

In step c), the initial composition 14 is processed through a refiner 18to form the mulch composition or growing medium 20. The refiner 18 mayuse a plurality of disks to obtain the mulch composition or fibrousgrowing medium 20. The refiner 18 may use two or more disks, one ofwhich is rotating, to separate wood fibers from each other as set forthin U.S. Pat. No. 2,757,150, the entire disclosure of which is herebyincorporated by reference. The refiner 18 is usually operated at a lowertemperature than the temperature used in step b). The refiner 18 may beoperated at a temperature in the range of about 70° F. (21° C.) to about400° F. (204° C.), about 150° F. (66° C.) to about 350° F. (176° C.),about 200° F. (93° C.) to about 300° F. (148° C.). The refiner 18 may beoperated under steam. The refiner 18 may be operated at atmosphericpressure or elevated pressures such as pressures of about 50 lb/in² (3.5kg/cm²) or lower to about 100 lb/in² (7.0 kg/cm²). Some of theadditional components 22 may be added during step c) such as a dye or asurfactant.

In step d), the mulch composition or growing medium 20 is dried attemperatures of about 400° F. (204° C.) to about 600° F. (316° C.) forthe time sufficient to reduce the moisture content of the mulchcomposition or growing medium 20 to a value less than about 45 weight %,less than about 25 weight %, or less than about 15 weight %, based onthe total weight of the mulch composition or growing medium 20. Thedrying step may be about 1 to 10 seconds long, about 2 to 8 secondslong, about 3 to 5 seconds long. The drying step may be longer than 10seconds. Exemplary equipment for drying of the mulch composition orgrowing medium 20 in step d) may be a flash tube dryer capable of dryinglarge volumes of mulch composition or growing medium 20 in a relativelyshort length of time due to the homogeneous suspension of the particlesinside the flash tube dryer. While suspended in the heated gas stream,maximum surface exposure is achieved, giving the growing medium uniformmoisture. The moisture content of the mulch composition or growingmedium 20 may be from about 10 to about 50 weight %, about 20 to about40 weight %, about 25 to about 35 weight % of the total weight of themulch composition or growing medium 20.

In an optional step e), the mulch composition or growing medium 20 isfurther refined, and the additional components 22 set forth above may beadded.

As was stated above, the mulch composition or growing medium may be usedas a stand-alone mulch composition or growing medium. Alternatively, themulch composition or growing medium may be added to a conventional mulchcomposition, growing medium, growing mix, or substrate to replace atleast partially one or more components. The mulch composition or growingmedium may displace peat, composted pine bark, perlite, vermiculite,sand, rock wool, compost, animal manure, rice hulls, hardwood bark,softwood bark, coir, other organic materials such as composted organicmatter, the like, or a combination thereof. The mulch composition orgrowing medium may displace, in order of increasing preference, about0.5% or more, 1% or more, 5% or more, 10% or more, 15% or more, 20% ormore, 25% or more, 30% or more, 40% or more, 45% or more, 50% or more,60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 99%or more of at least one of the components named above in a growing mix,based on the total weight of the mulch composition or growing mix. Themulch composition or growing medium may replace about 1 to 99, 10 to 95,20 to 80, 30 to 70, 40 to 50 weight % of one or more components in theconventional mulch composition or growing medium, based on the totalweight of the mulch composition or growing medium. The mulch compositionor growing medium may replace about 1 to 99, 2 to 95, 5 to 87, 7 to 85,10 to 80, 15 to 75, 20 to 70, 25 to 65, 30 to 60, 25 to 55, 30 to 50, 35to 45, 38 to 42 volume % of one or more components in the conventionalmulch composition or growing medium, based on the total volume of themulch composition or growing medium. An exemplary conventional growingmix may contain, based on the total weight of the growing mix, about 80weight % of peat and 20 weight % of perlite, which is being added tocreate air space for the peat. An alternative example, the substratecontains 70 weight % peat and 30 weight % growing medium. Yet anotherexample substrate contains 50 weight % peat and 50 weight % growingmedium. In a yet alternative embodiment, the substrate contains 30weight % peat and 70 weight % growing medium. The growing medium of thepresent invention may replace the perlite entirely and replace at leastabout 50 weight % of the peat. The resulting growing medium is thusenvironmentally advantageous as it contains only a relatively low amountof peat and more economical than the conventional growing mix due toreplacement of perlite. The resulting growing medium also provides abetter balance of air and water retention than the peat-perlite andother conventional growing mixes.

Table 1 below illustrates the benefit of combining the growing mediumhaving a bulk density from about 1.2 lbs/ft³ (19.2 kg/m³) to about 1.7lbs/ft³ (27.0 kg/m³) with peat having a bulk density from about 7.7(123.3 kg/m³) to about 11.5 lbs/ft³ (184.2 kg/m³). The higher the ratioof growing medium, the lower the resulting combined bulk density and thegreater the resulting recoverable volume. Peat is the primary componentused in soiless substrates. Yet, due to its weight, up to about 50% ofthe delivery cost of peat is due to freight or transportation costs. Theintroduction of the growing medium into the peat substantially increasesthe volume of a peat soiless substrate while reducing the freight ortransportation cost.

TABLE 1 Density reduction of a peat substrate by addition of the growingmedium (GM) Substrate Substrate Bulk Density Bulk Density DensitySubstrate Decrease in Type of [lb/ft³]/[kg/m³] [lb/ft³]/ ReductionIncrease in Transportation Substrate peat GM [kg/m³] [%] Volume [%] cost[%] 70 vol. % peat, 7.7-11.5/ 1.25-1.7/ 5.75-8.6/ 25.3 33.9 25.3 30 vol.% GM 123.34-184.21 20.02-27.23 92.11-137.76 50 vol. % peat, 7.7-11.5/1.25-1.7/ 4.5-6.6/ 41.5 71 41.5 50 vol. % GM 123.34-184.21 20.02-27.2372.08-105.72 20 vol. % peat, 7.7-11.5/ 1.25-1.7/ 2.5-3.7/ 67.5 209 67.580 vol. % GM 123.34-184.21 20.02-27.23 40.05-59.27 5 vol. % peat,7.7-11.5/ 1.25-1.7/ 1.5-2.2/ 80.5 414 80.5 95 vol. % GM 123.34-184.2120.02-27.23 24.03-35.24

Balanced air (non-capillary) and water (capillary) holding capacityprovides ideal growing conditions to plants. The volume of air space isimportant for root systems and plants in general, as without oxygen,roots cannot grow and absorb water or minerals. The more oxygenated theroots are, the more efficient the plants become in converting sugarsinto energy for plant growing. Likewise, sufficient water retention ofthe growing medium is important to ensure that the roots have access toproper amount of water for photosynthesis, root growth, and efficientuptake of water by the growing plant without being oversaturated. Yet,the conventional mulch compositions or growing mixes usually do notachieve balanced air and water retention as typically, when the volume %of water retention rises, it is at the expense of air retention and viceversa.

The mulch composition or growing medium of the present inventionadvantageously can provide balanced air and water holding capacity atabout 25-60 volume % each, preferably between about 43-56 volume % each,more preferably about 48-49 volume % each, based on the total volume ofthe mulch composition or growing medium, measured in a container havingdimensions 30.5×30.5×30.5 cm (12×12×12 inches). The air and waterholding capacity may each be without limitation, about 20 volume % ormore, 25 volume % or more, 30 volume % or more, 35 volume % or more, 40volume % or more, 45 volume % or more, 50 volume % or more, 55 volume %or more, 60 volume % or more, or 65 volume % or more, of the totalvolume of the mulch composition or growing medium, when measured in30.5×30.5×30.5 cm (12×12×12 inches) container.

Water and air holding capacity, as referred to herein, are measuredaccording to “Procedures for Determining Physical Properties ofHorticultural Substrates Using the NCSU Porometer by HorticulturalSubstrates Laboratory,” Department of Horticultural Science, N.C. StateUniversity in Raleigh, N.C., which is incorporated in its entirety byreference herein. The water holding capacity is measured by a ContainerCapacity test which measures the percent volume of a substrate that isfilled with water after the growing medium is saturated and allowed todrain. It is the maximum amount of water the growing medium can hold.The drainage is influenced by the height of the substrate; this propertyis thus dependent on container size. The taller the container, the moredrainage it will cause, and the less capacity of the substrate to holdwater. The oxygen holding capacity is measured as percent volume of asubstrate that is filled with air after the growing medium is saturatedand allowed to drain. It is the minimum amount of air the material willhave. It is affected by the container height in reverse fashion tocontainer capacity; i.e., the taller the container, the more drainageand therefore more air space.

The sum of water and air holding capacity equal total porosity for agiven density and moisture content. Total porosity defines the totalvolume of pores and refers to percent volume of a substrate that iscomprised of pores, or holes. It is the volume fraction which providesthe water and aeration in a substrate. The total porosity+the percentsolids=100%. Total porosity of the mulch composition or growing mediummay be about 88 to about 99 volume %, about 91 to about 98 volume %,about 93 to about 97 volume %, about 94 to about 96 volume %. Totalporosity of the mulch composition or growing medium may be about 88 vol.% or more, 91 vol. % or more, 93 vol. % or more, 95 vol. % or more, 97vol. % or more, 99 vol. % or more.

The water holding capacity (WHC) of the mulch composition or growingmedium may be also measured by ASTM D7367-14, a standard test method fordetermining water holding capacity of fiber mulches for hydraulicplanting. According to ASTM D7367-14, the water holding capacity (WHC)of the mulch composition or growing medium may be about 400 to about1000 weight %, about 500 to 1000 weight %, about 600 to 900 weight %,based on the total weight of the mulch composition or growing medium.

Alternatively still, the air holding capacity of the mulch compositionor growing medium may be assessed based on a water retention curvecomparison focusing on the amount of water which is available to theplant once grown in the mulch composition or growing medium. Substrates,both soil-based and soil-less, may be classified based on particle andpore size analysis as either uniform, well, or gap graded. Uniformgraded substrates include particles and pores of similar diameter. Anexample of a uniform substrate may be sand. Well graded substratesinclude particles and pores of various sizes, but contain a consistentgradation of the particles from large particles to fine particles. In awell graded substrate, the pore spaces also range between large andfine. A well graded substrate is, for example, silt loam. Gap gradedsubstrates, on the other hand, include large particles and fineparticles, but lack intermediately sized particles. Thus, the pores in agap graded substrate are either large or small, and a gap ofintermediate or mid-size particles exists. An example gap gradedsubstrate is bark.

Large particles are particles greater than 2.35 mm in diameter, mid-sizeparticles have a diameter between 0.71 mm and 2.35 mm, and small or fineparticles have a diameter smaller than 0.71 mm. The pore cavitiescreated between particles depend on the size of the particles. Thelarger the particles, the larger the pores between the particles. Thesize distribution of particles and pores influences how water moveswithin a substrate. When intermediate sized pores are absent, water doesnot move easily between the large and small pores. Thus, a missing poresize may cause a break in hydraulic conductivity. Water may still movefrom the large pores to the small pores, but the transport happens viavapor phase transport instead of direct water flow. An optimal growingsubstrate is a well graded substrate having large, mid-size, and smallparticles and pores. A well graded substrate is capable of maintaininghydraulic conductivity which is beneficial to maximizing plant availablewater. The gradual particle distribution in a well graded substrate thusallows continuous movement of water from large to small pores.

The mulch composition or growing medium represents a well gradedsubstrate which maintains hydraulic conductivity, provides a highpercentage of available water to the plant, but unlike other well gradedsubstrates, the growing medium also maintains high porosity. The growingmedium may be used by itself or as a filler of other substrates to cureone or more of their deficiencies such as lack of intermediately sizedparticles. The growing medium may fill the spaces between the particlesof a different substrate without clogging pore spaces. The addition ofthe growing medium may increase the volume of medium and small pores ina substrate, increase porosity and available water while reducingdensity of the substrate.

Tables 2-4 below provide comparison of particle distribution in varioussubstrates and the growing medium (GM). Whole Tree Substrate (WTS)refers to a pine tree substrate containing pine wood, pine bark, andneedles processed by hammer milling. Pine Tree Substrate (PTS) refers toa substrate containing pine wood chips processed by hammer milling.

TABLE 2 Substrate particle distribution in substrates and growing mediumcontaining 100 vol./wt. % of one type of substrate or growing medium.Type of Substrate [100 vol. %] GM Peat Perlite Bark Sieves ParticleParticle Particle Particle Particle [Mesh/ Range Distribu- Distribu-Distribu- Distribu- μm] [mm] tion [%] tion [%] tion [%] tion [%]1/4″/ >6.3 0.3 8.9 0.0 25.2 6300 #4/ 4.75-6.2 0.1 6.1 2.0 9.6 4750 #8/2.36-4.74 12.4 17.8 52.8 28.1 2360 #16/ 1.18-2.35 23.8 18.1 23.9 16.71180 #25/ 0.71-1.17 24.2 20.1 8.8 11.0 710 #50/ 0.3- 21.5 20.2 11.8 9.2300 0.7 #100/ 0.15-0.29 10.3 6.9 0.8 0.2 150 Pan/ <0.15 7.3 1.9 0.0 0.0<150

In at least one embodiment, about 70 to 96 wt./vol. % of the totalweight/volume of the growing medium has a particle size smaller than orequal to 4750 μm and larger than or equal to 150 μm. In anotherembodiment, about 70 to 96 wt./vol. % of the total weight/volume of thegrowing medium has a particle size smaller than or equal to 4750 μm andlarger than or equal to 150 μm. Alternatively, about 64 to 96 wt./vol. %of the total weight/volume of the growing medium has a particle sizesmaller than or equal to 4750 μm and larger than or equal to 150 μm. Inone or more embodiments, about 62.3 to 79.5 wt./vol. % of the totalweight/volume of the growing medium has a particle size smaller than orequal to 4750 μm and larger than or equal to 150 μm. About 90 to 99wt./vol. % of the total weight/volume of the growing medium has aparticle size smaller than or equal to 4750 μm and larger than or equalto 150 μm. Alternatively still, about 90 to 95 wt./vol. % of the totalweight/volume of the growing medium has a particle size smaller than orequal to 4750 μm and larger than or equal to 150 μm.

In one or more embodiments, about 70 to 96 wt./vol. % of the totalweight/volume of the growing medium has a particle size smaller than orequal to 2360 μm and larger than or equal to 150 μm. In anotherembodiment, about 70 to 96 wt./vol. % of the total weight/volume of thegrowing medium has a particle size smaller than or equal to 2360 μm andlarger than or equal to 150 μm. Alternatively, about 64 to 96 wt./vol. %of the total weight/volume of the growing medium has a particle sizesmaller than or equal to 2360 μm and larger than or equal to 150 μm. Inone or more embodiments, about 62.3 to 79.5 wt./vol. % of the totalweight/volume of the growing medium has a particle size smaller than orequal to 2360 μm and larger than or equal to 150 μm. About 77 to 96wt./vol. % of the total weight/volume of the growing medium has aparticle size smaller than or equal to 2360 μm and larger than or equalto 150 μm. Alternatively, about 80 to 90 wt./vol. % of the totalweight/volume of the growing medium has a particle size smaller than orequal to 2360 μm and larger than or equal to 150 μm. About 56 to 86wt./vol. % of the total weight/volume of the growing medium has aparticle size smaller than or equal to 2360 μm and larger than or equalto 150 μm.

In one or more embodiments, about 40 to 80 wt./vol. % of the totalweight/volume of the growing medium has a particle size greater than orequal to 710 μm and less than or equal to 1180 μm. Alternatively, about36 to 86 wt./vol. % of the total weight/volume of the growing medium hasa particle size greater than or equal to 710 μm and less than or equalto 1180 μm. In one or more embodiments, about 39 to 70 wt./vol. % of thetotal weight/volume of the growing medium has a particle size greaterthan or equal to 710 μm and less than or equal to 1180 μm. About 40 to55 wt./vol. % of the total weight/volume of the growing medium has aparticle size greater than or equal to 710 μm and less than or equal to1180 μm. Alternatively still, about 45 to 50 wt./vol. % of the totalweight/volume of the growing medium has a particle size greater than orequal to 710 μm and less than or equal to 1180 μm.

In one or more embodiments, about 10.1 to 25.0 wt./vol. % of the totalweight/volume of the growing medium has a particle size greater than orequal to 2360 μm and less than or equal to 4750 μm. Alternatively, about4.0 to 31.0 wt./vol. % of the total weight/volume of the growing mediumhas a particle size greater than or equal to 2360 μm and less than orequal to 4750 μm. In one or more embodiments, about 12.5 to 20.5wt./vol. % of the total weight/volume of the growing medium has aparticle size greater than or equal to 2360 μm and less than or equal to4750 μm. About 10.0 to 23.5 wt./vol. % of the total weight/volume of thegrowing medium has a particle size greater than or equal to 2360 μm andless than or equal to 4750 μm. Alternatively still, about 12.0 to 23.0wt./vol. % of the total weight/volume of the growing medium has aparticle size greater than or equal to 2360 μm and less than or equal to4750 μm.

TABLE 3 Substrate particle distribution in substrates containing 100vol. % of one type of substrate. Type of Substrate [100 vol. %] SievesCoir WTS PTS [Mesh/ Particle Particle Particle Particle μm] Range [mm]Distribution [%] Distribution [%] Distribution [%] 1/4″/ >6.3 0.0 0.035.8 6300 #4/ 4.75-6.2 0.2 0.2 17.1 4750 #8/ 2.36-4.74 6.6 14.0 27.82360 #16/ 1.18-2.35 24.6 42.0 12.3 1180 #25/ 0.71-1.17 26.2 24.2 5.2 710#50/ 0.3- 40.0 14.9 1.7 300 0.7 #100/ 0.15-0.29 1.9 4.1 0.1 150 Pan/<0.15 0.5 0.7 0.0 <150

TABLE 4 Substrate particle distribution in substrates to which eithergrowing medium, perlite, WTS, or PTS was added. Type of Substrate 50vol. % 70 vol. % 80 vol. % 80 vol. % 70 vol. % 70 vol. % Peat, 50 vol.Peat, 30 vol. Bark, 20 vol. Peat, 20 vol. Peat, 30 vol. Peat, 30 vol. %GM % GM % GM % Perlite % WTS % PTS Sieves Particle Particle ParticleParticle Particle Particle Particle [Mesh/ Range DistributionDistribution Distribution Distribution Distribution Distribution μm][mm] [%] [%] [%] [%] [%] [%] ¼″/6300 >6.3  0.6 1.1 8.4 1.75 0.5 21.0 #4/4750 4.75-6.2  2.4 1.7 7.7 2.1 1.0 10.1  #8/2360 2.36-4.74 6.6 9.624.8 15.0 10.0 16.3  #16/1180 1.18-2.35 14.4 12.2 20.8 12.3 18.9 10.6#25/710 0.71-1.17 27.9 17.2 13.3 15.2 16.9 10.4 #50/300 0.3-0.7 30.530.6 17.5 35.3 28.9 18.8 #100/150  0.15-0.29 11.2 20.2 6.9 14.9 18.2 8.9 Pan/<150 <0.15 6.6 7.4 0.5 3.5 5.5 4.0

The available water of various substrates and the growing medium wasassessed using a Hyprop. Hyprop is a modular lab instrument capable ofgenerating a moisture characteristic curve of a sample material anddetermines the unsaturated hydraulic conductivity of a sample material.Hyprop measures loss of conductivity of water in a substrate. Accordingto Pertassek, T., A. Peters and W. Durner (2015), “[t]his method usesweight changes of samples and the matric potential measurements in thesamples during a drying process caused by evaporation to derive soilhydraulic functions.” As each sample dries, water within the samplecontinually moves from the larger to smaller pores until the water canno longer move easily due to a gap in the grading of the substrate. Atthat point, Hyprop begins to measure the unsaturated hydraulicconductivity.

During the testing, 250 cm³ cores/sampling rings were packed to a knowndensity with substrates 1-5 and allowed to sub-irrigate. The Hyprop unitand two tensiometers, at two different lengths, were filled withdegassed water and inserted into the packed cores. Each core+Hyprop wasplaced on a scale, and available water was monitored as each sampledried. During the monitoring, a computer equipped with softwarecollected several thousand measurements for each sample. Based on thecollected data points, the software generated a water release curve andthe point of unsaturated hydraulic conductivity (UHC) for each sample.UHC indicates a point at which a plant starts to experience waterstress.

Table 5 below, as well as FIGS. 9 (sample nos. 1-3) and 10 (sample nos.4 and 5), show the results of the Hyprop measurements for differentsubstrates. Volumetric Water Content (VWC) at 1 pF is a commonlyaccepted threshold for container capacity or water holding capacity in asubstrate. The UHC break relates to a specific volumetric water contentat which hydraulic conductivity breaks in each substrate. The UHC breakthus indicates, for each substrate, when the substrate begins to performsub-optimally with regard to providing available water to the plant. Theavailable water is the difference between VWC at 1 pF and VWC at UHCbreak.

TABLE 5 Hyprop test results Volumetric Volumetric Water UHC WaterContent Sample Type of Content Break at UHC Break Available no.Substrate at 1 pF [%] (pF) [%] Water [%] 1 70 vol. % 81.77 1.99 36.2445.53 peat, 30 vol. % GM 2 70 vol. % 78.40 1.84 48.28 30.12 peat, 30vol. % PTS 3 70 vol. % 79.30 1.76 43.27 36.03 peat, 30 vol. % WTS 4 80vol. % 71.51 1.91 32.99 38.52 peat, 20 vol. % perlite 5 80 vol. % 74.572.07 34.29 40.28 peat, 20 vol. % perlite

Additional testing was performed with four different samples, each ofwhich contained 80 vol. % of peat and the remained formed by an additionof perlite, vermiculite, coir, or growing medium (GM), respectively. Thetesting incorporated yet another methodology of assessing data regardingavailable water, specifically pressure plate testing. For each sample, asix-inch cylinder was filled with the material and allowed to saturatein a water bath for 24 hours. The cylinder was removed from the waterbath without allowing it to drain and was weighed to calculate saturatedbulk density. The cylinder was allowed to drain freely for 2 hours andwas weighed again. Each sample was then placed in an oven for 24 hoursto dry and then re-weighed. The measured values, along with the knownvolume of the cylinder, water retention, air space, and solids werecalculated as volume percentages in the container. To determineavailable water at different pressures, a smaller cylinder was used(pressure cores) for each sample in a similar fashion except thecylinder was placed under 2 centibars (2,000 Pa) of pressure in apressure pot for 24 hours and then weighed. The measured value, alongwith the porosity determined in the six-inch cylinder, was used todetermine available water at the specific pressure. The measurement wasrepeated at 24 hour intervals for the 10 centibar (10,000 Pa) and 50centibar (50,000 Pa) values. Readily available water is the volumetricwater content between 2 centibars (2,000 Pa) and 50 centibars (50,000Pa). Potentially available water relates to the amount of availablewater after adding back 50% of the water that was held in the substrateat 50 centibars (50,000 Pa) of pressure. Available water improvementexpresses how much more available water there is when peat is amendedwith GM versus perlite, vermiculite, and coco pith at 20% inclusionrates.

TABLE 6 Test data for a substrate containing 80 vol. % peat and 20 vol.% substitute measured by pressure plate testing Potentially AvailableTotal Container Available Available Water Type of Porosity WaterCapacity Air Space Water Water Improvement Substrate [%] [%] [%] [%] [%][%] 80 vol. % peat, 85.2 65.5 19.7 32.9 49.2 10 20 vol. % perlite 80vol. % peat, 85.1 67.1 17.9 30.3 48.7 19.5 20 vol. % vermiculite 80 vol.% peat, 86.3 68.6 17.7 26.5 47.6 36.6 20 vol. % coco pith 80 vol. %peat, 89.3 67.6 21.6 36.2 51.9 — 20 vol. % GM

Compared to other substrates, the growing medium processed in thepressurized vessel by a process described above has fiber which isthinner and longer, which has higher surface area ratio, much lowerdensity, as well as smaller median particle diameter, as is shown inTable 7 below. The surface area ratio refers to the following formula:10/median particle diameter/dry bulk density. The smaller the medianparticle diameter at the lower density equates to higher surface area ofthe particles. Due to the growing medium preparation process describedherein, the lignin with the growing medium components melts and theresultant fiber is shaped differently compared to other media. Forexample, coir particles are generally spherical in shape with a smalleraspect ratio than the growing medium fiber. Bark particles and perliteare generally cylindrical. Peat, PTS, and WTS particles are moreelongated than coir, bark, and perlite, but remain wider and shorterthan growing medium fiber. Example particles and fibers are shown inFIGS. 1A-8B.

TABLE 7 Median particle diameter, dry bulk density, and surface arearatio of various substrates and of the growing medium. The dry bulkdensity was assessed using a container of the following dimensions: 30.5× 30.5 × 30.5 cm (12 × 12 × 12 inches). Type of Substrate [100 vol. %]GM Peat Perlite Bark Coir PTS WTS Median Particle 0.92 1.24 2.57 3.450.84 5.00 1.35 Diameter [mm] Dry Bulk Density [kg/l] 0.02 0.08 0.06 0.190.09 0.13 0.14 Surface Area Ratio 549.1 106.4 65.4 15.4 127.4 15.3 54.2

Additionally, the fiber's average length to width ratio is significantlygreater in the growing medium than in other substrates, as is evidencedin Table 8 below. Since water is held by surface tension along thelength of the fiber, the longer the fiber is, the more water can be heldby the substrate. Since the growing medium has fiber with greater lengthto width ratio than other substrates, the growing medium has higheravailable water and allows for development of a plant root ball in afaster manner. Additionally, the elongated fiber of the growing mediumprovides reinforcement of the substrate in a planting container. Since acontainer plant can be sold once it can be successfully removed from thecontainer and a substrate does not fall away from the roots, using thegrowing medium as a substrate or as a filler to a different substrateincreases plant establishment and thus results in a faster crop turn.

TABLE 8 Average length to width ratio of particles in sieves #16 and #50of various substrates and of the growing medium. Sieve #16/1180 μm Sieve#50/300 μm 1.18-2.36 mm Particle Range 0.30-0.71 mm Particle Range Typeof Substrate Average length to Width Ratio Range Average length to WidthRatio Range [100 vol. %] Lower Higher Lower Higher GM 14.899:1 30.602:139.615:1 55.507:1 Peat  1.463:1  2.010:1 3.498:1  6.323:1 Perlite 1.070:1  1.133:1 1:1  1.260:1 Bark  1.255:1  1.520:1 1.702:1  2.019:1Coir  1.720:1  1.840:1 1.051:1  1.349:1 PTS  7.260:1  7.392:1 2.543:114.497:1 WTS  1.805:1  4.368:1 4.942:1 13.329:1

In at least about one embodiment, about 10 to 80 weight % of the growingmedium has fiber with an average length to width ratio, also referred toas an aspect ratio, of 14:1 to 31:1. In an alternative embodiment, atleast about 20 to 70 weight % of the growing medium has fiber with anaverage length to width ratio of 14:1 to 31:1. In a yet anotherembodiment, about 30 to 60 weight % of the growing medium has fiber withan average length to width ratio of 14:1 to 31:1. Alternatively, atleast about 40 to 50 weight % of the growing medium has fiber with anaverage length to width ratio of 14:1 to 31:1. Alternatively still,about 15 to 40 weight % of the growing medium has fiber with an averagelength to width ratio of 14:1 to 31:1. In another embodiment, about 18to 30 weight % of the growing medium has fiber with an average length towidth ratio of 14:1 to 31:1.

In at least one embodiment, about 10 to 80 weight % of the growingmedium has fiber with an average length to width ratio of 39:1 to 56:1.In an alternative embodiment, about 20 to 70 weight % of the growingmedium has fiber with an average length to width ratio of 39:1 to 56:1.In a yet another embodiment, about 30 to 60 weight % of the growingmedium has fiber with an average length to width ratio of 39:1 to 56:1.Alternatively, about 40 to 50 weight % of the growing medium has fiberwith an average length to width ratio of 39:1 to 56:1. Alternativelystill, about 15 to 40 weight % of the growing medium has fiber with anaverage length to width ratio of 39:1 to 56:1. In another embodiment,about 18 to 30 weight % of the growing medium has fiber with an averagelength to width ratio of 39:1 to 56:1.

At least about 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65,70, 75, 80, 85, 90 weight % of the growing medium fibers have an averagelength to width aspect ratio equal to or greater than 8:1, 9:1, 10:1,14:1, 15:1, 18:1, 20:1, 22:1, 25:1, 18:1, 30:1 in sieve #16. About 10 to80, 20 to 70, 30, to 60, 40 to 50 weight % of the growing medium fiberhas the aspect ratio of equal to or greater than 8:1, 9:1, 10:1, 14:1,15:1, 18:1, 20:1, 22:1, 25:1, 18:1, 30:1 in sieve #16.

At least about 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65,70, 75, 80, 85, 90 weight % of the growing medium fibers have an averagelength to width aspect ratio equal to or greater than 16:1, 18:1, 20:1,22:1, 24:1, 26:1, 28:1, 30:1, 32:1, 33:1, 34:1, 36:1, 38:1, 39:1, 40:1,42:1, 44:1, 46:1, 48:1, 50:1, 52:1, 55:1 in sieve #50. About 10 to 80,20 to 70, 30 to 60, 40 to 50 weight % of the growing medium fiber hasthe aspect ratio of equal to or greater than 16:1, 18:1, 20:1, 22:1,24:1, 26:1, 28:1, 30:1, 32:1, 33:1, 34:1, 36:1, 38:1, 39:1, 40:1, 42:1,44:1, 46:1, 48:1, 50:1, 52:1, 55:1 in sieve #50.

At least about 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65,70, 75, 80, 85, 90 volume % of the growing medium fibers have an averagelength to width aspect ratio equal to or greater than 8:1, 9:1, 10:1,15:1, 18:1, 20:1, 22:1, 25:1, 18:1, 30:1 in sieve #16. About 10 to 80,20 to 70, 30 to 60, 40 to 50 volume % of the growing medium fiber hasthe aspect ratio of equal to or greater than 8:1, 9:1, 10:1, 15:1, 18:1,20:1, 22:1, 25:1, 18:1, 30:1 in sieve #16.

At least about 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65,70, 75, 80, 85, 90 volume % of the growing medium fibers have an averagelength to width aspect ratio equal to or greater than 16:1, 18:1, 20:1,22:1, 24:1, 26:1, 28:1, 30:1, 32:1, 33:1, 34:1, 36:1, 38:1, 39:1, 40:1,42:1, 44:1, 46:1, 48:1, 50:1, 52:1, 55:1 in sieve #50. About 10 to 80,20 to 70, 30 to 60, 40 to 50 volume % of the growing medium fiber hasthe aspect ratio of equal to or greater than 16:1, 18:1, 20:1, 22:1,24:1, 26:1, 28:1, 30:1, 32:1, 33:1, 34:1, 36:1, 38:1, 39:1, 40:1, 42:1,44:1, 46:1, 48:1, 50:1, 52:1, 55:1 in sieve #50.

At least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 weight % of the fibers, basedon the total weight of the fibers, have an average length to width ratioof about 8:1 to 35:1, 10:1 to 30:1, 12:1 to 28:1, 15:1 to 25:1, 18:1 to23:1, 20:1 to 22:1 in sieve #16, and/or 15:1 to 60:1, 20:1 to 55:1, 25:1to 50:1, 28:1 to 45:1, 25:1:40:1, 28:1 to 38:1, 30:1 to 35:1 in sieve#50. Alternatively, at least about 1 to 90, 10 to 80, 20 to 70, 30 to60, 40 to 50 weight % of the fibers, based on the total weight of thefibers, have an average length to width ratio of at about 8:1 to 35:1,10:1 to 30:1, 12:1 to 28:1, 15:1 to 25:1, 18:1 to 23:1, 20:1 to 22:1 insieve #16, and/or 15:1 to 60:1, 20:1 to 55:1, 25:1 to 50:1, 28:1 to45:1, 25:1:40:1, 28:1 to 38:1, 30:1 to 35:1 in sieve #50.

At least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50,55, 60, 65, 70, 75, 80, 85, 90, 95 volume % of the fibers, based on thetotal volume of the fibers, have an average length to volume ratio ofabout 8:1 to 35:1, 10:1 to 30:1, 12:1 to 28:1, 15:1 to 25:1, 18:1 to23:1, 20:1 to 22:1, 9:1 to 50:1, 13.5:1 to 34:1, 14:1 to 32:1 in sieve#16, and/or 15:1 to 60:1, 20:1 to 55:1, 25:1 to 50:1, 28:1 to 45:1,25:1:40:1, 28:1 to 38:1, 30:1 to 35:1, 30:1 to 70:1, 37:1 to 62:1, 38:1to 60:1 in sieve #50. Alternatively, about 1 to 90, 10 to 80, 20 to 70,30 to 60, 40 to 50 volume % of the fibers, based on the total volume ofthe fibers, have an average length to width ratio of about 8:1 to 35:1,10:1 to 30:1, 12:1 to 28:1, 15:1 to 25:1, 18:1 to 23:1, 20:1 to 22:1 insieve #16, and/or 15:1 to 60:1, 20:1 to 55:1, 25:1 to 50:1, 28:1 to45:1, 25:1:40:1, 28:1 to 38:1, 30:1 to 35:1 in sieve #50.

An additional advantage of the mulch composition or growing medium ofthe present invention is lower dry bulk density as well as wet bulkdensity when compared to prior art substrates. High density may imposetransportation limits on the mulch compositions or growing substrates assuch substrates may reach their weight limit before they reach thevolume limit feasible for transportation. When compared to higherdensity media, the lower wet and dry bulk densities of the present mulchcomposition or growing medium provide greater volume of the mulchcomposition or growing medium to the end user at the same weight. Thelow density mulch composition or growing medium of the present inventionmay be added as a component to prior art mulches or growing media andthus lower their transportation costs by about 5% or more, 10% or more,15% or more, or 20% or more, as compared to the prior art media alone.Additionally, a consumer may find it easier to purchase and utilize thegrowing medium of the present invention because of its lower weight. Thedry bulk density of the growing medium may be, in order of increasingpreference, about 6 lb/ft³ (96.11 kg/m³) or less, 4 lb/ft³ (64.07 kg/m³)or less, 3 lb/ft³ (48.06 kg/m³) or less, or 2 lb/ft³ (32.04 kg/m³) orless. The dry bulk density of the mulch composition or growing mediummay be about 1.5 lb/ft³ (24.03 kg/m³) to about 6 lb/ft³ (96.11 kg/m³),about 2 lb/ft³ (32.04 kg/m³) to about 4 lb/ft³ (64.07 kg/m³), about 2.2lb/ft³ (35.24 kg/m³) to about 2.6 lb/ft³ (41.65 kg/m³). The wet bulkdensity of the mulch composition or growing medium may be, in order ofincreasing preference, about 15 lb/ft³ (240.28 kg/m³) or less, 10 lb/ft³(160.18 kg/m³) or less, 8 lb/ft³ (128.15 kg/m³) or less, 6 lb/ft³ (96.11kg/m³) or less, 4 lb/ft³ (64.07 kg/m³) or less, 3 lb/ft³ (48.06 kg/m³)or less, or 2 lb/ft³ (32.04 kg/m³) or less. The wet bulk density of themulch composition or growing medium may be about 1 lb/ft³ (16.02 kg/m³)to about 20 lb/ft³ (320.37 kg/m³), about 2.2 lb/ft³ (35.24 kg/m³) toabout 10 lb/ft³ (160.18 kg/m³), about 2.4 lb/ft³ (38.44 kg/m³) to about15 lb/ft³ (240.28 kg/m³), about 2.6 (41.65 kg/m³) to 10 lb/ft³ (160.18kg/m³), about 2.8 lb/ft³ (44.85 kg/m³) to about 7 lb/ft³ (112.13 kg/m³),about 3.0 lb/ft³ (48.06 kg/m³) to about 5 lb/ft³ (80.09 kg/m³).

Table 9 below illustrates test results for one embodiment of a mulchcomposition or growing medium comprising about 80% wood components andabout 20% tree bark and another embodiment comprising 100% pine woodfiber, based on the total weight of the mulch composition or growingmedium, in comparison to prior art growing media.

TABLE 9 Mulch/growing media properties Volume Volume of of air space -Moisture Mulch/growing air space range Dry bulk density Wet bulk densitycontent medium [vol. %] [vol. %] [lb/ft³] [kg/m³] [lb/ft³] [kg/m³] [%]Mulch/growing 30.25 25-75 2.37 37.96 2.83 45.33 90.99 medium of presentinvention (80% wood, 20% bark) Mulch/growing 44.53 25-75 2.20 35.24 2.4939.89 89.80 medium of present invention (100% pine wood fiber) SphagnumPeat 10.22  5-25 4.25 68.08 12.04 192.86 85.78 ⅜″ 24.00 20-45 9.64154.42 23.82 381.56 75.99 Hammermilled Bark Retruder Processed 14.69 —7.46 119.50 19.85 317.49 84.56 Bark Coir Block Fiber 15.36 — 4.42 70.8032.55 521.40 89.33

The data in Table 9 was collected by JR Peters Laboratory Allentown,Pa., USA, using “Procedures for Determining Physical Properties ofHorticultural Substrates Using the NCSU Porometer by HorticulturalSubstrates Laboratory,” Department of Horticultural Science, N.C. StateUniversity in Raleigh, N.C., which is incorporated in its entirety byreference herein.

The percent volume of air space in Table 9 refers to the air holdingcapacity discussed above which was measured as the percent volume of asubstrate that is filled with air after the material is saturated andallowed to drain. It is the minimum amount of air the material willhave. The analysis using the NCSU Porometer was performed on a 28.3inch³ (463.8 cm³) sample in a 3×3 inches (7.6×7.6 cm) aluminum cylinder.

The bulk density in Table 9 refers to the ratio of the mass of drysolids to the bulk volume of the substrate. The bulk volume includes thevolume of solids and pore space. The mass is determined after drying apacked core to constant weight at 221° F. (105° C.), and volume is thatof the sample in cylinders.

The moisture content in Table 9 refers to the percent moisture found ina sample on a wet mass basis. This is calculated by: [(Wet weight−Dryweight)/Wet weight]×100. It denotes how much of a particular sample iscomprised of water.

Table 10 provides comparison of prior art growing media with twoembodiments of the present invention, specifically one embodiment of amulch composition or growing medium comprising about 80% wood componentsand about 20% tree bark and another embodiment comprising 100% pine woodfiber, based on the total weight of the mulch composition or growingmedium. The loose bulk density data in Table 7 was gained by packing themulch composition or growing medium into a container measuring30.5×30.5×30.5 cm (12×12×12 inches) after the mulch composition orgrowing medium was expanded by an opener and/or by using a processrecommended for the specific kind of a mulch composition or growingmedium.

TABLE 10 Loose bulk density Expanded bulk density including Net dryweight moisture content of the expanded bulk Mulch/growing mulch/growingmedium density medium [lb/ft³] [kg/m³] [lb/ft³] [kg/m³] Mulch/growing 1.2-1.75 19.22-28.03  0.9-1.35 14.42-21.62  medium of present invention(80% wood, 20% bark) Mulch/growing 1.0-1.65 16.02-26.43 0.75-1.2512.01-20.02  medium of present invention (100% pine wood fiber) SphagnumPeat  9.0-12.5 144.17-200.23  5.0-6.85 80.09-109.73 3/8″ Hammermilled23-33 368.43-528.61 11.0-17.5 176.20- Composted Pine 280.32 Bark 3/8″Hammermilled 15-20 240.28-320.37 7.5-10  120.14- Aged Pine Bark 160.19

Table 11 provides a size classification of the fiber of the mulches orgrowing media; the weight % of material passing through various sievesizes as well as density, WHC, and total porosity are also provided.Total porosity was measured by the porometer testing “Procedures forDetermining Physical Properties of Horticultural Substrates Using theNCSU Porometer by Horticultural Substrates Laboratory,” as referencedabove.

TABLE 11 Wood fiber size classification Materials: wt. % woodcomponents/wt. % bark Particle 90%/10% 70%/30% 50%/50% 30%/70% 10%/90%size ranges Sieves #8/2360 [wt. %] 15.9 26.7 21.0 8.6 4.7 4-25 Mesh/μm#16/1180 [wt. %] 23.8 16.3 9.6 10.1 8.9 9-30 #25/710 [wt. %] 25.0 14.912.5 13.7 10.1 15-35  #50/300 [wt. %] 20.7 17.6 25.6 27.0 25.4 15-30 #100/150 [wt. %] 10.0 13.5 15.4 21.1 20.4 6-15 pan/<150 [wt. %] 4.6 11.015.9 19.5 26.4 2-20 Total Porometer [vol. %] 96-99 94-98 93-97 91-9588-94 88-99  porosity Density Range [lb/ft³]; 1.5-2.0; 1.5-2.5;2.0-3.25; 3.0-5.0; 3.5-6.5; 1.5-6.5; [kg/m³] 24-32 24-40 32-52 48-8056-104 24-104 WHC ASTM D7367- 825-925 725-825 625-725 500-625 400-500 —14 [wt. %]

The sieve size of the fiber particles in the end product may range fromUS sieve size #8 to #100, but other sieve sizes are contemplated. Thesize of the fiber in the mulch composition or growing medium may rangefrom about 0.149 mm to about 2.36 mm. Some of the wood components and/orbark may be processed in such a way that they become a powder with aparticle size of about 30 μm or smaller to about 600 μm or larger.Generally, the smaller the fiber size, the higher the WHC.

In the Table 11 above, 79.5% of the wood/bark fiber components of thecomposition having 90 wt. % wood components and 10 wt. % bark, has aparticle size smaller than 2360 μm and larger than 150 μm. 62.3% of thewood/bark fiber components of the composition having 70 wt. % woodcomponents and 30 wt. % bark has a particle size smaller than 2360 μmand larger than 150 μm. 63.1% of the wood/bark fiber components of thecomposition having 50 wt. % wood components and 50 wt. % bark has aparticle size smaller than 2360 μm and larger than 150 μm. 71.9% of thewood/bark fiber components of the composition having 30 wt. % woodcomponents and 70 wt. % bark has a particle size smaller than 2360 μmand larger than 150 μm. 64.8% of the wood/bark fiber components of thecomposition having 10 wt. % wood components and 90 wt. % bark has aparticle size smaller than 2360 μm and larger than 150 μm.

In an alternative embodiment, 70 to 90 wt. % of the fibrous woodcomponents have a particle size smaller than 2360 μm and larger than 150μm. In at least one embodiment, 55 to 90 wt. % of the fibrous woodcomponents have a particle size smaller than 2360 μm and larger than 150μm. In another embodiment, 63.1 to 79.5 wt. % % of the fibrous woodcomponents of the composition have a particle size smaller than 2360 μmand larger than 150 μm.

About 10.1 to 25.0 wt. % of the fibrous wood components have a particlesize greater than 710 μm and less than 1180 μm. In an alternativeembodiment, about 12 to 20 wt. % of the fibrous wood components have aparticle size greater than 710 μm and less than 1180 μm. Alternativelystill, about 15 to 18 wt. % of the fibrous wood components have aparticle size greater than 710 μm and less than 1180 μm.

At least about 10 to 90, 20 to 80, 30 to 70, 40 to 60 weight % of fibershaving a particle size from 150 μm to 2360 μm have an average aspectratio of at least 9:1 to 55:1, 9.5:1 to 50:1, 10:1 to 45:1, 11:1 to40:1, 12:1 to 38:1, 13:1 to 35:1, 13.5:1 to 34:1, 14:1 to 33.5:1, or14.5:1 to 33.1.

The mulch composition or growing medium may be also used in hydraulicapplications. The hydraulically-applied mulch composition or growingmedium presents an effective solution for restoration of vegetation anderosion control. The hydraulically-applied mulch composition or growingmedium may bond directly to soil while protecting seed, thus shelteringseedlings and/or plants from wind, heavy rain, and other environmentalconditions while allowing seed germination and plant growth. Thehydraulically-applied mulch composition or growing medium may be used tosecure statically-compromised slopes, stabilize highly erodible soil,reintroduce native species of plants, the like, or a combinationthereof. The hydraulically-applied mulch composition or growing mediummay be used alone or in combination with other erosion-control methods.The hydraulically-applied mulch composition or growing medium may beused during highway projects, recreational projects such as golfcourses, in mine reclamation areas, in industrial or other applications.

The hydraulically-applied mulch composition or growing medium may beapplied to a site at once or in a plurality of stages. The mulchcomposition or growing medium may be mixed together with water, andoptionally seed, chemical binders, natural gums, and/or interlockingmanmade fibers, and/or other components in a tank of a hydro-sprayingmachine or another suitable equipment. The seed may contain one speciesor comprise a mix of species such as native or non-native grasses,wildflowers, forbs, or other desirable species. The mixing may continueuntil all fiber of the mulch composition or growing medium issubstantially broken apart and hydrated. When proper viscosity andactivation of bonding additives is achieved, additional components namedabove or other components such as fertilizers, macronutrients, and/ormicronutrients, may be added. The hydrated mulch composition or growingmedium may be then applied onto the site from a suitable equipment suchas a hydro-spraying machine with a fan-type nozzle. Immediately afterapplication, the mulch composition or growing medium bonds directly tothe soil and provides protection for dormant seed, minimizes soil loss,and assists in fast establishment of vegetation at the application site.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A growing medium comprising: about 20 to about 70weight % fibrous tree bark, based on the total weight of the growingmedium; and about 30 to about 80 weight % fibrous wood components, basedon the total weight of the growing medium, wherein the growing mediumhas a dry bulk density of about 48 kg/m³ or lower and wet bulk densityof about 120 kg/m³ or lower.
 2. The growing medium of claim 1, whereinthe growing medium has a total porosity of 88 volume % or more.
 3. Thegrowing medium of claim 1, wherein the growing medium has a totalporosity of 95 volume % or more.
 4. The growing medium of claim 2,wherein water holding capacity of the growing medium according to ASTMD7367-14 is about 400 to 1000 weight %, based on the total weight of thegrowing medium.
 5. The growing medium of claim 1, wherein 62.3-79.5% ofthe fibrous tree bark and the fibrous wood components have a particlesize less than 2380 μm and greater than 150 μm.
 6. The growing medium ofclaim 4, wherein the growing medium comprises about 10.1-25.0 weight %fibrous tree bark and fibrous wood components, based on the total weightof the growing medium, having a particle size greater than 710 μm andless than 1180 μm.
 7. The growing medium of claim 4, further comprisingat least one of fertilizer(s), macronutrient(s), micronutrient(s),mineral(s), chemical binder(s), natural gum(s), interlocking manmadefiber(s), soil, or seed.
 8. The growing medium of claim 4, wherein thefibrous wood components comprise refined wood chips, wood fiber, orboth.
 9. The growing medium of claim 4, wherein the fibrous tree barkcomprises pine tree bark.
 10. The growing medium of claim 4, wherein thegrowing medium comprises about 50 to about 60 weight % fibrous tree barkand about 40 to about 50 weight % fibrous wood components, based on thetotal weight of the growing medium.
 11. The growing medium of claim 4,wherein the growing medium comprises about 10 to about 60 weight %fibrous tree bark and about 40 to about 90 weight % fibrous woodcomponents, based on the total weight of the growing medium.
 12. Thegrowing medium of claim 11, wherein the growing medium is sterile.
 13. Agrowing mix composition comprising: about 40 to 85 weight % growingmedium including fibrous tree bark and fibrous wood components; andabout 15 to 60 weight % peat, wherein the growing medium has totalporosity of 91 volume % or more.
 14. The growing mix composition ofclaim 13, wherein the growing mix is substantially free of perlite. 15.The growing mix composition of claim 14, wherein the growing mediumfurther comprises at least one of fertilizer(s), macronutrient(s),micronutrient(s), mineral(s), chemical binder(s), natural gum(s),interlocking manmade fiber(s), soil, or seed.
 16. The growing mixcomposition of claim 13, further comprising composted pine bark,vermiculite, sand, rock wool, compost, animal manure, rice hulls,hardwood bark, softwood bark, coir, or a combination thereof.
 17. Thegrowing mix composition of claim 13, wherein the growing mediumcomprises about 5 to about 95 weight % fibrous tree bark and about 5 toabout 95 weight % fibrous wood components, based on the total weight ofthe growing medium.
 18. The growing mix composition of claim 17, whereinthe fibrous tree bark comprises pine tree bark.
 19. The growing mixcomposition of claim 18, wherein the growing medium has a dry bulkdensity between 24 and 104 kg/m³.
 20. A growing medium comprising: about100 weight % fibrous pine wood components, wherein the growing mediumhas a dry bulk density of 12.01 to 20.02 kg/m³ and wet bulk density ofabout 120 kg/m³ or lower, wherein the growing medium has a totalporosity of 91 volume % or more, and wherein water holding capacity ofthe growing medium according to ASTM D7367-14 is about 400 to 1000weight %, based on the total weight of the growing medium.
 21. Thegrowing medium of claim 20, wherein the growing medium is sterile.